The present invention relates to an objective lens actuator of an optical pickup for conducting reading/writing from/onto a disc within an optical disc drive, an optical pickup comprising this objective lens actuator therein, and an optical disc drive comprising this optical pickup therein.
In recent years, advancement of high density is achieved in the optical discs, and as a method for dealing with that, mainly, wavelength of a laser is shortened or an aperture of an objective lens is enlarged. For this reason, ill influences upon the quality of an optical spot become large due to inclination of the objective lens with respect to the optical disc. Since deterioration of a signal of the optical spot due to the inclination of the objective lens is also linked up with the deterioration of a signal when recording/reproducing, there is brought about a necessity of suppressing a tilt between the optical disc and the objective lens.
In such optical disc drive, an objective lens actuator is a device for driving the objective lens for focusing lights upon a recording surface upon the optical disc into the followings: a focusing direction (i.e., a direction of approaching/parting from the surface of the optical disc), a tracking direction (i.e., a radial direction of the optical disc), and a radial tilt direction (i.e., inclining into a radial direction of the optical disc).
In such the objective lens actuator, a support arrangement for a moving portion, which is made up with a lens holder equipped with the objective lens and coils thereon, is arranged in such a manner that elastic support members, each one end thereof being fixed on the moving portion and each other end thereof on a fixed portion, i.e., straight wires build up a plural number of parallel links.
As a method for suppressing the tilt between the optical disc and the objective lens is disclosed an objective lens actuator for adjusting the tilt of the objective lens in the radial direction of the disc, in the following Patent Document 1. Also, in the following Patent Document 2 is disclosed an objective lend actuator, in which the fixed portion of the elastic support members displaceable in an axial direction is divided so that the effective length of the elastic members can be adjusted, independently, and thereby unevenness in spring stiffness of the elastic support members is corrected so as to bring an initial tilt characteristic thereof to a preferable one.
[Patent Document 1] Japanese Patent Laying-Open No. 2003-228852 (2003); and
[Patent Document 2] Japanese Patent Laying-Open No. 2008-084398 (2008).